X Ray Spectra And Moseley S Law

Let's analyze both statements provided regarding X-ray spectra of elements.

1. Understanding Statement I: "A plot of (where is the frequency of X-rays emitted) vs atomic mass is a straight line."
   • The relation of frequency of emitted X-rays is better understood through Moseley's law, which states that the square root of the frequency of the characteristic X-ray is proportional to the atomic number (Z) of the element and not the atomic mass.
   • Moseley’s law is mathematically represented as , where and are constants. This shows a linear relationship between and , not atomic mass.
   • Thus, Statement I is false because the correct plot should involve atomic number, not atomic mass.
2. Understanding Statement II: "A plot of (where is the frequency of X-rays emitted) vs atomic number is a straight line."
   • According to Moseley’s law, the plot involving the square root of the frequency is what exhibits linearity with the atomic number, not the frequency itself.
   • A direct plot of frequency vs is not linear, as the relationship involves the square root of frequency.
   • Thus, Statement II is also false.

After careful examination of both statements based on Moseley’s law, both statements are found to be false. Therefore, the correct answer is:

Both Statement I and Statement II are false.